The present invention relates to an apparatus for guiding and cutting a continuously advancing yarn, and winding initial layers thereof during a package doff in a takeup device, as well as to a method of guiding and cutting a continuously advancing yarn. An apparatus and method of this general type are known from EP 0 311 827.
In textile machines, for example, a crimped yarn is continuously wound to a package. After the package is completely wound, it is doffed. To this end, it is necessary that the yarn be first cut, so that the full package with the loose yarn end can be replaced with a new empty tube. During the doff, the yarn end of the continuously advancing yarn is received and removed by a pneumatic suction device. After completion of the package doff, the yarn is caught by means of a catching device and wound on the new tube.
In the apparatus and method disclosed in EP 0 311 827, the yarn is guided by a movable yarn guide outside of the winding range to a suction device laterally adjacent the winding range, after the package is fully wound. After completion of the package doff, and once the new tube is ready for catching, the yarn guide is pivoted back to the winding range. To transfer or catch the yarn, a transfer device deflects the yarn between the suction device and the yarn guide and offers it to the yarn catching device for engagement.
The known apparatus and method have the disadvantage that at the end of a winding cycle , the loose yarn end lies against the fully wound package in an undefined manner, which complicates locating the loose yarn end in particular in the further processing.
Furthermore, the deflection of the yarn by the transfer device for engaging the yarn leads to considerable looping, which results in major tension fluctuations in the yarn in proportion with the winding tension. Such tension fluctuations may lead to lapping on upstream feed elements.
It is accordingly an object of the invention to provide an apparatus and method of the initially described kind, so as to ensure that during a package doff, when the yarn is guided and caught, and when first layers thereof are wound, the yarn is guided as gently as possible with little deflection.
A further object of the invention is to ensure after cutting the yarn that the loose yarn end lies against a tie-off bead of the full package, and that the advancing yarn is threaded on a new tube without substantial slack.